The present invention relates to a floating caliper disc brake, with a brake support member arranged on one side of the brake disc and including two arms, with a brake shoe guided and supported on the arms, and with a brake caliper carried and guided on the brake support member and arranged to frictionally engage the brake shoe.
In a known disc brake (German Pat. No. DT-OS 2,636,443) one brake shoe is guided and carried between two supporting surfaces of the brake support member by means of two pins secured to the brake caliper, while the other brake shoe is formed fast with the brake caliper. The brake caliper possesses two guide bolts guided through two interference fits on the brake support member in such a manner that they are in positive engagement with the brake support member only towards the center of the brake. When the brake is actuated, the brake force occurring on that brake shoe that is in positive engagement with the brake caliper is transmitted, through the brake caliper and the guide bolts extending in the disc entry direction, to the arm of the brake support member extending in the disc entry direction, and the brake force occurring on the other brake shoe is transmitted through the supporting surface of the brake support member directly to the arm of the brake support member lying on the disc exit side.
While this arrangement ensures distribution of the total frictional force occurring to both arms of the brake support member under any load condition, one brake shoe transmits the frictional force acting on it always to only one arm of the brake support member. From this arrangement there results that one brake shoe is pushed while the other is pulled. As a consequence, the brake shoes are subject to force relationships favoring intense brake vibration and brake squeal. Moreover, the brake caliper and guide bolt constructions involve high expenditure of material because they are required to take up and transmit the entire frictional force acting on a brake shoe.
Another disc brake (German Pat. No. DT-AS 2,031,249) shows two Z-shaped members placed on the brake support member, guiding the brake caliper and supporting it if a load is applied. The inward brake shoe on the side close to the piston is disposed between the arms of the brake support member, and the outward brake shoe embraces the arms of the brake support member so that it is able to bear with its end against outward supporting surfaces of the arms of the brake support member, which surfaces are turned away from each other.
Thus, in the event of a load being applied, the brake shoes are always in frictional engagement with only one arm of the brake support member, and only after a deformation of the arm of the brake support member lying on the disc entry side occurs, which deformation is determined by the existing clearances, is the brake caliper clamped between its guides and constitutes a force-transmitting connection between the arms of the brake support member.
The disadvantage therein is that the distribution of force is dependent upon the manufacturing tolerances of the guides of the brake caliper and that a plurality of individual components are required. In addition, the distribution of force occurs only after the deformation of one brake support member arm and after clearances are overcome which differ for each brake. Even slightest dimensional tolerances affect the distribution of force to a great extent.